<!DOCTYPE html>
<html lang="en" xmlns:v-text="http://www.w3.org/1999/xhtml">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script src="http://cdn.jsdelivr.net/npm/vue/dist/vue.js"></script>
</head>
<body>
<div id="app">
    <span v-text:="message">Test Hello</span>
    <span v-html="message">Test Hello2</span>
</div>

<script type="text/javascript">
    var app = new Vue({
        el:"#app",
        data:{
          message:"<h1>Hello Vue</h1>",
        }
    });
</script>

</body>
</html>